Reproduction Abstracts

Human embryonic stem cells (hESCs) are derived from the inner cell mass of the blastocyst. They proliferate by self-renewal and have the potential to develop into all cells of the three germ layers. Thus, hESCs hold great potential for use in regenerative medicine. hESCs are difficult to maintain in culture and have a tendency to spontaneously differentiate. Culture at a low, 5% oxygen concentration is beneficial for the maintenance of a wholly pluripotent cell population compared to atmospheric oxygen but the mechanism which regulates this hypoxic response is not known. We hypothesise that culture under hypoxic conditions alters the expression of microRNAs (miRNAs) to promote stem cell maintenance. Three low-density miRNA arrays were performed on hESCs cultured at either 5 or 20% oxygen to investigate differentially expressed miRNAs. In total, 231 miRNAs were expressed in hESCs and 40 miRNAs were found to be differentially expressed at 5% oxygen compared to 20% oxygen. miR-210 was found to be consistently upregulated in hESCs cultured at hypoxic conditions compared to atmospheric oxygen. This finding was validated using qPCR and miR-210 expression was found to be fourfold greater (P<0.05) in Hues7 hESCs cultured at 5% oxygen compared to 20% oxygen. Bioinformatic and in silico analyses on differentially expressed miRNAs are being used to predict those which may target key genes regulating stem cell fate. These data suggest that environmental oxygen tension regulates the expression of miRNAs in hESCs.

Research funded by the Gerald Kerkut Charitable Trust, University of Southampton and the Society for Reproduction and Fertility.